SWIP Internal Wall Insulation System

SWIP IWI system components SWIP Internal Wall Insulation provides a system based approach to internal wall insulation. The system has been tested and certified to demonstrate that all components work together as designed to deliver the required performance. The SWIP IWI System is designed for upgrading existing solid (or cavity) external walls. It consists of thermally engineered composite studs and insulation slabs, which can be combined to provide greater thicknesses of high-performance thermal insulation than achievable by using a single thickness. SWIP Studs are a composite of high performance extruded polystyrene insulation and Oriented Strand Board (OSB). Traditional internal wall insulation which uses traditional timber or metal studs leads to thermal bridging through the studs. This needs to be compensated for by increasing the thickness of the overall system. The innovative use of the thermally insulated SWIP Studs within the SWIP system prevents this and results in an overall thinner system.The SWIP IWI System has been designed to simplify the process of upgrading existing solid (and cavity) masonry walls whilst delivering high levels of thermal performance. Typical U-values.

U-values (W/m2K)
SWIP Stud thickness (mm) SWIP Stud with
SWIPStud with SWIP Batt &
35mm SWIP PIR Laminate
SWIP Stud with SWIP Batt &
50mm SWIP PIR Laminate
65 0.43 0.29 0.25
95 0.30 0.22 0.19
2 x 65 0.24 0.19 0.17

For project specific calculations contact our Technical Advice and Support Centre on 0845 402 3585

System Components

SWIP Stud – Extruded polystyrene bonded to Oriented Strand Board (OSB)

SWIP Batt – Water repellent glass mineral wool slab

Plasterboard fixing – Drywall screws

Sealant – SWIP multi-purpose sealant


Fixing to masonry – SWIP IWI fixings manufactured in accordance with BS1210

Wall plugs – SWIP IWI wall plugs

SWIP Vapour Control Layer – vapour resistance of 260MN.s/g

SWIP Reveal Boards – Extruded polystyrene bonded to plasterboard. Extruded polystyrene with a cement screen either side